One thing I (and many non-technical friends) found creepy recently is how Google Maps monitors your phone camera. An update quietly pushed this on-by-default feature for the purpose of prompting you to add images to their product.
Edit: looks like they have pushed out at least two new on-by-default features since I wrote this (not that long ago); 'photo view count opportunities' and 'new and popular places'.
Well, "monitors your phone camera" is a very misleading way to put it. They "monitor" your photo library, in a way that I think most people would expect. If you take a picture with the GPS on, obviously your phone knows where you are, it's not that weird to ask you something based on your location. I don't think most people expect Google Maps to be completely disconnected from the rest of their Google phone.
OK, I could have been more precise in my wording. I meant that it monitor photos that you take with your phone camera not that it constantly monitors what the camera sees. I didn't intend to mislead and I think that's a reasonable interpretation.
I still think that this is unexpected behaviour. It belongs in the camera app, not the maps app. The expectation is that apps are sand-boxed and separate from each other.
I have anecdotal evidence from friends who don't normally care about issues like this. Yet they felt compelled enough to pro-actively share this with comments similar to "NO GOOGLE!", which suggests it's not just me.
I wrote more on this and how to disable it here: https://unop.uk/on-google-maps-geotagging-and-privacy
Edit: looks like they have pushed out at least two new on-by-default features since I wrote this (not that long ago); 'photo view count opportunities' and 'new and popular places'.